Photoionization time delays

International audienceThe material presented in this chapter is based on important advances realized in " attophysics " which make feasible to follow the motion of electrons in atoms and molecules with attosecond-level time resolution. In this context, time-delays have been recently determined in the process of photoionization by extreme-ultraviolet (xuv) pulses and the question of the significance of these measured delays arises. As we shall outline here, numerical experiments show that they are intimately related to the structure of the ionized species' continuous spectrum. Another point addressed here is that, in experiments, the measurements have the common characteristic to be performed in the presence of an auxiliary infra-red (IR) field, used to " clock " the timing of the process. This implies to adapt the theory treatment to handle such " two-color " photoionization processes. We review a systematic analysis of these features that are characteristic of this class of electronic transitions, when viewed in the time domain

Strong-field photoionization by circularly polarized light

We demonstrate that strong-field ionization of atoms driven by circularly polarized light becomes an adiabatic process when described in the frame rotating with the laser field. As a direct consequence, a conservation law emerges: in the rotating frame the energy of the tunneling electron is conserved for rotationally invariant potentials. This conservation law, arising from a classical picture, is retrieved through a proper classical-quantum correspondence when considering the full quantum system, beyond the Strong Field Approximation

Etude théorique des processus électroniques au cours de collisions ion-atome et ion-molécule

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Journée Technique Cap'Vert 3ème édition - Posters présentés dans les ateliers

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Journée technique Cap'Vert. 2ème édition

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